forestry-final-1
Terms
undefined, object
copy deck
- anizotropic
- =wood exhibits different physical properties (strength, shrinking, swelling, compression) when tested along 3 tree directional axes
- properties characteristic of certain species only
-
variation between woods in:
a. specific gravity
b. hardness
c. strength properties
d. mashining
e. gluing
f. durability
g. reaction to chemicals - which factors determine the properties of wood?
-
a. growth
b. structure
c. composition of the material - 3 surfaces of wood
-
a. transverse (cross-sectional) surface is used the most
b. tangential surface
c. radial surface - cross section of a wood fiber (inside to out)
-
a. lumen
b. secondary wall
c. primary wall
d. middle lamella - what is the distribution of content of wood
-
cellulose (40-50%)
hemicellulose (20-30%)
lignin (15-30%)
- properties common to all woods
-
a. all tree stems have a predominately vertical arrangement of cells
b. all wood is cellular in structure
c. all wood contains cellulose, hemicellulose, and lignin
d. all wood is anizotropic
e. all wood is hygroscopic - what is the result of moisture variations?
- - it produces dimensional changes which are due to its anisotropic nature, unequal in the n= three tree directions
- why is it relevant to distinguish between certain species?
- -must have positive identification as a basis for its manufacturing, marketing, and proper use
- 3 tree directional axes
-
a. radial
b. tangential
c. longitudinal - why is understanding the properties of wood important?
- -to utilize the wood correctly
- which wood fibers are on average longer, softwoods (coniferous) or hardwoods (deciduous)
- softwoods (coniferous)
- variablity within a species
-
a. variablity from tree to tree
b. variability in wood taken from different places
c. variability within a given piece of wood (early or late wood) - what are the fundamental studies of wood
-
a. properties that are common to all woods
b. properties that are characteristic only to certain species
c. degree of variability of properties that may be present within a species - hygroscopic
- =wood loses and gains moisture as a result of changes in the atmospheric humidity and temperature